Method and system for sharing over-allocated bandwidth between different classes of service in a wireless network

ABSTRACT

A method and system for sharing over-allocated bandwidth between different classes of service in a wireless network. Traffic is transmitted for a first service class in excess of bandwidth allocated to the first service class using unused bandwidth allocated to a second class. After transmitting traffic for the first service class in excess of bandwidth allocated to the first service class using unused bandwidth allocated to a second class, traffic for a third service class is transmitted in unused bandwidth remaining in the second service class.

TECHNICAL FIELD OF THE INVENTION

This invention relates in general to the field of wirelesscommunications, and more particularly to a method and system for sharingover-allocated bandwidth between different classes of service in awireless network.

BACKGROUND OF THE INVENTION

Wireline and wireless Internet protocol (IP) networks have traditionallysupported a best effort delivery of all traffic. To support enhancedservices, multiple types, or classes, of services have been establishedand assigned certain class of service (CoS) parameters that helpengineer queues for each service type.

The CoS parameters include delay, jitter, error rates, and throughput.The CoS parameters can be provisioned on a per IP connection or per flowbasis through mechanisms such as resource reservation protocol (RSVP) orcan be provisioned on aggregate flows which are classified into serviceclasses. Internet service providers (ISPs) can utilize the serviceclasses, their associated CoS behavior and CoS provisioning to providetiered service offerings to their business and consumer customers.

Typically, each service class is allocated a bandwidth to transportcorresponding traffic in accordance with the CoS policy. The allocationof bandwidth prevents starvation traffic flows at each CoS level.Traffic in excess of the allocated bandwidths for a service class isheld, or dropped causing delay and/or retransmissions.

SUMMARY OF THE INVENTION

The present invention provides a method and system for sharingover-allocated bandwidth between different classes of service in awireless network that subsequently reduce or eliminate problems anddisadvantages with previous systems and methods. In a particularembodiment, the present invention uses excess bandwidth from one or moreservice classes to satisfy excess demand in other service classes.

In accordance with one embodiment of the present invention, a method forsharing over-allocated bandwidth between service classes in a wirelessnetwork includes transmitting traffic for a first service class inexcess of bandwidth allocated to the first service class using unusedbandwidth allocated to a second class. After transmitting traffic for afirst service class in excess of bandwidth allocated to the firstservice class using unused bandwidth allocated to a second class,traffic for a third service class is transmitted in unused bandwidthremaining in the second service class.

Technical advantages of one or more embodiments of the present inventioninclude more efficient use of the bandwidth available in a wirelesssector by sharing over-allocated bandwidth between different classes ofservice. Other advantages may include fewer packet and/or call drops andthus reduced retransmissions. Additionally, call capacity of the networkis increased while preventing class starvation by allocating bandwidthto each class and using over-allocated bandwidth for excess traffic inother classes.

Other technical advantages of the present invention will be readilyapparent to one skilled in the art from the following figures,description, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and itsadvantages, reference is now made to the following description, taken inconjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram illustrating a communications network inaccordance with one embodiment of the present invention;

FIG. 2 is a diagram illustrating allocation of bandwidths in a wirelesssector of FIG. 1 in accordance with one embodiment of the presentinvention; and

FIG. 3 is a flow diagram a method for sharing over-allocated bandwidthbetween different classes of service in a wireless sector in accordancewith one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the communications system 10 includes a wirelessnetwork 12 connected to a wireline network 14 through a gateway 16.

The wireless network 12 includes a number of base stations (BTSs) 30connected to base station controllers (BSCs) 32. The BTSs 30 each covera geographic region or cell or sector 34 of the wireless network 12 andcommunicate with mobile devices 36 in the cell 34. The mobile devices 36may be cell phones, data phones, portable data devices, portablecomputers, handheld devices, handsets, portable network appliances orother suitable devices capable of communicating information over awireless link 38.

The BSCs 32 are connected to each other in some way, to the Gateway 16and to a mobile switching center (MSC) 40. The BSCs 32 and the MSC 40cooperate to provide switch and handoff functionality for the wirelessnetwork 12. In this way, voice, video, data and other information isrouted to and from the mobile devices 36 and connections are maintainedwith the mobile devices 36 as they move throughout, or roam the wirelessnetwork 12.

Wireless link 38 is a radio frequency (RF) link. The wireless link 38may be based on established technologies or standards such as IS-54(TDMA), IS-95 (CDMA), GSM and AMPS, 802.11 based WLAN, or more recenttechnology such as CDMA 2000 and W-CDMA or proprietary radio interfaces.In a particular embodiment, wireless link 38 comprises a code divisionmultiple access (CDMA) link based on a CDMA standard and in whichpackets are segmented into radio frames for transmission over thewireless interface and reassembled by the receiving device toreconstitute the packets.

The wireline network 14 includes a packet or other suitable data network50 connecting a number of servers 52 to each other and to the gateway.The packet network 50 also connects the gateway, and thus the wirelessnetwork 12 to the public switched telephone network (PSTN). Accordingly,mobile devices 36 may communicate through wireless network 12, packetnetwork 50 and PSTN 54 with standard telephones, clients and computersusing modems or digital subscriber line (DSL) connections or othertelephony devices 58.

The data network 50 may be the Internet, intranet, extranet, or othersuitable local or wide area network capable of communicating informationbetween remote endpoints. For the Internet embodiment, information istransmitted in Internet protocol (IP) packets. It will be understoodthat information may be transmitted in other suitable packets, includingasynchronous transport mode (ATM) and other cells or datagrams.

The servers 52 may comprise voicemail servers (VMS), fax/modem servers,short message center (SMSC) servers, conferencing facilities,authentication, authorization, and accounting (AAA) servers, billingservers, home location registers (HLR), home subscriber servers (HSS),domain name servers (DNS) and other suitable servers and functionalityproviding services to mobile devices 36 and/or to wireless and/orwireline connections in the communications system 10.

The servers 52 and/or other elements of the wireless or wireline network12 store subscriber level information for users of the wireless and/orwireline network 12. The service level information includes service,quality and/or service level agreement (SLA) parameters for userconnections as well as rate and other subscription information. In aparticular embodiment, the BSCs 32 and/or Gateway 16 store or access SLAdatabases including a class of service (CoS) policy and rate informationfor each user. The CoS may be any suitable service level informationthat identifies parameters, such as drops, delays, jitters and otherlimits or levels for the user connections. It will be understood thatsubscription level information may be otherwise stored and/or accessedfor call set up and mobility processing by the communications network10.

Gateway 16 comprises a scheduler 17. In a particular embodiment, thescheduler 17 comprises logic encoded in media for implementing trafficallocation and other suitable functionality of the system.

FIG. 2 illustrates, in accordance with an embodiment of the presentinvention, discrete bandwidths allocated to different classes of servicein a wireless sector 34. The allocation of bandwidth prevents starvationby any service class, allows prioritization of transmission resources,and provides differentiated services.

Referring to FIG. 2, the horizontal axes of the graphs represent thepassage of time. Bandwidth is represented by the vertical axes. In aparticular embodiment, a bandwidth may be allocated to a best effort(BE) class of service 70, assured forwarding (AF) classes of service72–78, and an expedited forwarding (EF) class of service 80. It will beunderstood that the allocated bandwidths may comprise fewer, more,and/or different service classes. For example, the allocated bandwidthsmay comprise a class having a substantial guarantee of traffic arrival,a class with a limited such guarantee, and a class with no orsubstantially no such guarantee.

In a particular embodiment, the allocated bandwidth are constant orsubstantially constant. In other embodiments, the allocated bandwidthsmay vary and may be dynamically determined based on real-time operatingcharacter of 12. In either embodiment, the allocated bandwidth may bebased on the priority and/or rate of the corresponding traffic and thecurrent, estimated and/or anticipated traffic volume in the serviceclass. Another portion of the total available bandwidth may be allocatedto non-bursty traffic flows that are each substantially constant inbandwidth usage 82. The non-bursty traffic may include, for example,voice, video, and other real-time traffic connections.

At any given time, the amount of traffic for certain classes of servicemay consume more or less than the total amount of allocated bandwidth.Thus, bandwidths may be over-allocated for one or more service classeswhile under allocated for one or more remaining service classes. Thisexcess traffic 84 or excess bandwidth 86, respectively, may vary withtime. For example, at time t1, excess bandwidth is found in the EF, AF₂,AF₁, and voice allocated bandwidths while AF₄, and AF₃ allocatedbandwidths have excess traffic. At time t2, in contrast, EF, AF₄, AF₃,AF₂, and BE allocated bandwidths have excess bandwidth, while there isexcess traffic in AF₁ allocated bandwidth.

FIG. 3 shows a method for sharing over-allocated bandwidths betweendifferent classes of service in a wireless network in accordance withone embodiment of the present invention. In this embodiment, voicetraffic is considered as well as three classes of service for burstytraffic: EF, AF, and BE. If there is excess traffic, that traffic istransmitted using excess bandwidth in the following order: AF, BE, andthen EF. Excess voice bandwidth is used first, and then excess bandwidthfor the other classes in order of increasing priority: BE, AF, and EF.In this particular embodiment, excess bandwidth is first used fromnon-bursty service classes and then from bursty classes based onpriority. This provides maximum remaining bandwidth for the burstyclasses. In this embodiment, excess traffic for lower priority classesis placed in excess bandwidth of higher priority, bursty classes. Inother embodiments, excess lower-priority traffic may not be transmittedin over-allocated higher-priority class bandwidths.

Referring now to FIG. 3, and in accordance with an embodiment of thepresent invention, the method begins with step 100 wherein the scheduler17 in the gateway 16 transmits packet traffic in each class usingallocated bandwidth. At determination step 102, the scheduler 17determines whether there is excess of assured forwarding (AF) traffic.If there is excess AF traffic, the Yes branch leads to determinationstep 108. At determination step 108, the scheduler 17 determines whetherthere is an excess amount of voice bandwidth. If there is an excess ofvoice bandwidth, then, at step 110, excess AF traffic is transmittedusing the excess voice bandwidth. At determination step 132, if there isno remaining excess AF traffic, then the scheduler 17 moves on todetermination step 104 to determine whether there is excess traffic inthe next highest priority service class in which in the illustratedembodiment is BE.

Returning to determination step 132, if there is remaining excess AFtraffic after the excess voice bandwidth is fully used, then the Yesbranch of determination step 132 leads to determination step 112. The Nobranch of determination step 108 also leads to determination step 112.At step 112, if there is excess BE bandwidth, the excess AF traffic istransmitted in the excess BE bandwidth at step 114. At determinationstep 134, if there is no remaining excess AF traffic, then the schedulermoves on to determination step 104 to determine whether there is excessBE traffic.

Returning to determination step 134, if there is remaining excess AFtraffic after the excess BE bandwidth is fully used, then the Yes branchleads to determination step 116. The No branch of step 112 also leads todetermination step 116. At step 116, if there is not excess EF allocatedbandwidth, then all excess bandwidth from one, more or all usableservice classes has been fully used and the scheduler 17 has reached theend of the process. If at step 116 there is excess EF bandwidth, theexcess AF traffic is transmitted in the excess EF bandwidth at step 118.At determination step 136, if there is remaining excess AF traffic afterthe excess EF bandwidth is fully used, then all available excessbandwidth has been used and the scheduler has reached the end point ofthe process. If there is no remaining excess AF traffic, then thescheduler 17 moves on to determination step 104 to determine whetherthere is excess BE traffic.

At determination step 104, the scheduler 17 determines whether there isexcess best effort (BE) traffic. If there is excess BE traffic, the Yesbranch leads to determination step 120. At determination step 120, thescheduler 17 determines whether there is an excess amount of voicebandwidth. If there is an excess of voice bandwidth, then, at step 122,excess BE traffic is transmitted using the excess voice bandwidth. Atdetermination step 138, if there is no remaining excess BE traffic, thenthe scheduler 17 moves on to determination step 106 to determine whetherthere is excess traffic in the next priority service class in which inthe illustrated embodiment is EF.

Returning to determination step 138, if there is remaining excess BEtraffic after the excess voice bandwidth is fully used, then the Yesbranch of determination step 138 leads to determination step 124. The Nobranch of determination step 120 also leads to determination step 124.At step 124, if there is excess AF bandwidth, the excess BE traffic istransmitted in the excess AF bandwidth at step 126. At determinationstep 140, if there is no remaining excess BE traffic, then the schedulermoves on to determination step 106 to determine whether there is excessEF traffic.

Returning to determination step 140, if there is remaining excess BEtraffic after the excess AF bandwidth is fully used, then the Yes branchleads to determination step 142. The No branch of step 124 also leads todetermination step 142. At step 142, if there is not excess EF allocatedbandwidth, then all excess bandwidth from one, more or all usableservice classes has been fully used and the scheduler 17 has reached theend of the process. If at step 142 there is excess EF bandwidth, theexcess BE traffic is transmitted in the excess EF bandwidth at step 144.At determination step 146, if there is remaining excess BE traffic afterthe excess EF bandwidth is fully used, then all available excessbandwidth has been used and the scheduler has reached the end point ofthe process. If there is no remaining excess BE traffic, then thescheduler 17 moves on to determination step 106 to determine whetherthere is excess EF traffic.

At determination step 106, the scheduler 17 determines whether there isexcess expedited forwarding (EF) traffic. If there is excess EF traffic,the Yes branch leads to determination step 128. At determination step128, the scheduler 17 determines whether there is an excess amount ofvoice bandwidth. If there is an excess of voice bandwidth, then, at step130, excess EF traffic is transmitted using the excess voice bandwidth.At determination step 148, if there is no remaining excess EF traffic,then the scheduler 17 has reached the end of the process.

Returning to determination step 148, if there is remaining excess EFtraffic after the excess voice bandwidth is fully used, then the Yesbranch of determination step 148 leads to determination step 150. The Nobranch of determination step 128 also leads to determination step 150.At step 150, if there is excess BE bandwidth, the excess EF traffic istransmitted in the excess BE bandwidth at step 152. At determinationstep 154, if there is no remaining excess EF traffic, then the schedulerhas reached the end of the process.

Returning to determination step 154, if there is remaining excess EFtraffic after the excess BE bandwidth is fully used, then the Yes branchleads to determination step 156. The No branch of step 150 also leads todetermination step 156. At step 156, if there is not excess AF allocatedbandwidth, then all excess bandwidth from one, more or all usableservice classes has been fully used and the scheduler 17 has reached theend of the process. If at step 156 there is excess AF bandwidth, theexcess EF traffic is transmitted in the excess AF bandwidth at step 158.At this point all available excess bandwidth has been used and thescheduler has reached the end point of the process.

Although the present invention has been described with severalembodiments, a myriad of changes, variations, alterations,transformations, and modifications may be suggested to one skilled inthe art, and it is intended that the present invention encompass suchchanges, variations, alterations, transformations, and modifications asfall within the scope of the appended claims.

1. A method for sharing over-allocated bandwidth between service classesin a wireless network comprising: transmitting traffic for a firstservice class in excess of bandwidth allocated to the first serviceclass using unused bandwidth allocated to a third service class; andtransmitting the traffic for the first service class in unused bandwidthremaining in a second service class in cases where a bandwidthrequirement for the traffic is not met by using the unused bandwidthallocated to the third service class, wherein the second class comprisesnon-bursty traffic flows, and wherein the non-bursty traffic flowscomprises voice traffic, wherein the third service class comprises alower priority than the first service class and the second service classcomprises a lower priority than the first service class, and whereinunused voice bandwidth is used to accommodate the bandwidth requirementbefore using the unused bandwidth allocated to the third service.
 2. Themethod of claim 1, wherein the third service class comprises a besteffort (BE) class of service, the second service class comprises anassured forwarding (AF) class of service, and the first service classcomprises an expedited forwarding (EF) class of service.
 3. The methodof claim 1, further comprising: coordinating bandwidth for each of theservice classes such that the traffic is transmitted according to rulesassociated with the priorities of each of the service classes.
 4. Themethod of claim 1, wherein the first service class comprises videotraffic.
 5. A system for sharing over-allocated bandwidth betweenservice classes in a wireless network comprising: means for transmittingtraffic for a first service class in excess of bandwidth allocated tothe first service class using unused bandwidth allocated to a thirdservice class; and means for transmitting the traffic for the firstservice class in unused bandwidth remaining in a second service class incases where a bandwidth requirement for the traffic is not met by usingthe unused bandwidth allocated to the third service class, wherein thesecond class comprises non-bursty class of service (CoS), and whereinthe non-bursty CoS comprises voice traffic, wherein the third serviceclass comprises a lower priority than the first service class and thesecond service class comprises a lower priority than the first serviceclass, and wherein unused voice bandwidth is used to accommodate thebandwidth requirement before using the unused bandwidth allocated to thethird service.
 6. The system of claim 5, wherein the third service classcomprises a best effort (BE) class of service, the second service classcomprises an assured forwarding (AF) class of service, and the firstservice class comprises an expedited forwarding (EF) class of service.7. The system of claim 5, further comprising: means for coordinatingbandwidth for each of the service classes such that the traffic istransmitted according to rules associated with the priorities of each ofthe service classes.
 8. The system of claim 5 wherein the first serviceclass comprises video traffic.
 9. A system for sharing over-allocatedbandwidth between service classes in a wireless network comprising logicencoded in media, the logic operable to: transmit traffic for a firstservice class in excess of bandwidth allocated to the first serviceclass using unused bandwidth allocated to a third service class; andtransmit the traffic for the first service class in unused bandwidthremaining in a second service class in cases where a bandwidthrequirement for the traffic is not met by using the unused bandwidthallocated to the third service class, wherein the second class comprisesnon-bursty class of service (CoS), and wherein the non-bursty CoScomprises voice traffic, wherein the third service class comprises alower priority than the first service class and the second service classcomprises a lower priority than the first service class, and whereinunused voice bandwidth is used to accommodate the bandwidth requirementbefore using the unused bandwidth allocated to the third service. 10.The system of claim 9, wherein the third service class comprises a besteffort (BE) class of service, the second service class comprises anassured forwarding (AF) class of service, and the first service classcomprises an expedited forwarding (EF) class of service.
 11. The systemof claim 10, wherein the logic is further operable to: coordinatebandwidth for each of the service classes such that the traffic istransmitted according to rules associated with the priorities of each ofthe service classes.
 12. The system of claim 10, wherein the firstservice class comprises video traffic.
 13. A method for sharingover-allocated bandwidth between service classes in a wireless networkcomprising: transmitting traffic for a first service class in excess ofbandwidth allocated to the first service class using unused bandwidthallocated to a second class; and after transmitting traffic for a firstservice class in excess of bandwidth allocated to the first serviceclass using unused bandwidth allocated to a second class, transmittingtraffic for the first service class in unused bandwidth remaining in athird service class, wherein the second class comprises non-burstytraffic flows, and wherein the non-bursty traffic flows comprises voicetraffic, wherein the third service class comprises a lower priority thanthe first service class and the second service class comprises a lowerpriority than the first service class, and wherein unused voicebandwidth is used to accommodate the bandwidth requirement before usingthe unused bandwidth allocated to the third service.
 14. The method ofclaim 13, wherein the third service class comprises a best effort (BE)class of service, the second service class comprises an assuredforwarding (AF) class of service, and the first service class comprisesan expedited forwarding (EF) class of service.
 15. The method of claim13, further comprising: coordinating bandwidth for each of the serviceclasses such that the traffic is transmitted according to rulesassociated with the priorities of each of the service classes.
 16. Themethod of claim 13, wherein the first service class comprises videotraffic.
 17. A method for sharing over-allocated bandwidth betweenservice classes in a wireless network comprising: transmitting expeditedassured forwarding (AF) traffic in bandwidth allocated to AF traffic;transmitting best effort (BE) traffic in bandwidth allocated to BEtraffic; transmitting voice traffic in bandwidth allocated to voicetraffic; transmitting AF traffic in excess of bandwidth allocated to AFtraffic using unused bandwidth allocated to voice traffic if, aftertransmitting voice traffic in bandwidth allocated to voice traffic,bandwidth allocated to voice traffic is available; transmitting AFtraffic in excess bandwidth allocated to BE traffic if, aftertransmitting BE traffic in bandwidth allocated to BE traffic, bandwidthallocated to BE traffic is available and bandwidth allocated to voicetraffic is unavailable; and transmitting BE traffic in excess ofbandwidth allocated to BE traffic using unused bandwidth allocated tovoice traffic if, after transmitting voice traffic in bandwidthallocated to voice traffic and after transmitting AF traffic in excessof bandwidth allocated to AF traffic in bandwidth allocated to voicetraffic, bandwidth allocated to voice traffic is available, wherein theBE traffic comprises non-bursty traffic flows, and wherein thenon-bursty traffic flows comprises voice traffic.